The present invention relates to a composition for use in a water tank in the kitchen or sanitary sector.
Such compositions are known in numerous different forms for different applications, e.g. for deliming coffee machines or for cleaning and deliming toilets as an additive to cisterns.
The aim of the invention was to permit the simultaneous charging of substances possibly not completely compatible when used simultaneously and which evolve their functions at different, defined times.
DE-OS 20 65 153 and DE-OS 20 07 413 disclose detergent pellets for use as washing agents, in which it is inter alia provided to combine two components with different functionalities. The structure is formed from a covering or enveloping shell, which is e.g. formed from two shell halves, which comprise a cleaning agent, and a cavity surrounded by the shells and which contains additives such as softeners, brighteners, etc.
British patent 1 390 503 discloses a liquid cleaning agent or detergent which contains capsules, which are insoluble in the composition, but release their content when the composition is diluted with water. This objective is achieved in that the capsules are coated with a substance, which has a poor solubility in water solutions with a high ionic strength, but which is soluble if the ionic strength is reduced by dilution. It is pointed out that this procedure can be used in order to incorporate materials into the liquid cleaning agent, which in the latter are unstable or would produce an instability if added directly. It is also proposed to use this procedure for delaying the release of a specific substance.
U.S. Pat. No. 4,082,678 describes a fabric conditioner, which comprises a closed container containing a releasable agent and which is used for making water-insoluble or non-dispersible an inner container located in the first container and which is normally water-soluble or water-dispersible, the inner container containing a fabric conditioner.
Japanese patent applications KOKAI 60-141705, 61-28440, 61-28441, 61-28596, 61-28597 and 61-28598 describe processes for the production of pH-sensitive microcapsules for use in detergents. The pH-sensitive coating is a copolymer of the following monomers:
A) at least one basic monomer of formula I: 
in which R is hydrogen or a methyl group and R1 and R2 in each case an alkyl group with 1 to 3 carbon atoms and x is an integer from 1 to 4,
B) at least one monomer which is insoluble or difficultly soluble in water and
C) at least one water-soluble monomer.
It is pointed out that the described polymers are insoluble at a pH-value of 9.5 or higher and are soluble at a pH-value of 8.5 or lower. Different ingredients of cleaning agent compositions are described, which can be successfully and usefully coated with the described polymers. The aim of the invention described therein is to protect substances, which only evolve their function during the rinsing process up to the start of the latter and then to release them as immediately as possible. A disadvantage of the solution described in these Japanese patent applications is that the enveloped particles are in direct contact with non-alkaline washing water at the start of the washing cycle, which can give rise to a partial dissolving of the protective covering.
Japanese patent KOKAI 50-77406 discloses a washing aid, which is surrounded by a water-soluble covering or envelope, obtained by mixing polyvinyl acetal dialkyl aminoacetate and at least one organic acid, which is solid at room temperature. This protective envelope is intended to protect the washing aid during the main washing cycle and to release it during rinsing cycles. The described compound reacts to the pH-value change between the main washing cycle and the rinsing cycle. Here again the disadvantage exists of a possible partial dissolving of the protective envelope at the start of the washing cycle.
European patent applications EP 284 191 A2 and EP 284 334 A2 disclose a water-soluble polymer film for releasing washing additives during the rinsing cycle of washing machines, remaining intact during the normal washing cycle over a range of typical temperatures and rapidly dissolving during the rinsing cycle. These applications point out that the use of pH-sensitive coatings was admittedly known, but that these films are normally also temperature-sensitive, so that they do not remain reliably stable during the different temperatures of the washing cycle. The solution proposed is a pH-dependent material (which undesirably also has a positive, temperature-dependent dissolving behaviour) which is combined with a material having a negative, temperature-dependent dissolving behaviour. This combination is supposed to guarantee that the coatings do not dissolve at the high temperatures at the start of the washing cycle (in particular the very high temperatures occurring in American machines).
European patent application EP 481 547 A1 discloses multilayer dishwashing machine tablets having a core, a separating layer surrounding the core and an outer layer for the sequential release of the ingredients of the different layers. This tablet is fundamentally intended to solve two problems, namely 1) incompatible materials can be formulated together in a single tablet and released at different times in order to avoid mutual influencing and 2) compositions, which are intended to evolve their functions at different times, can be formulated in a single tablet.
One of the disadvantages of the prior art described in this document is that the only production process described is the successive moulding of the individual components. This gives rise to the risk that the core or core envelope is deformed, which can firstly lead to damage (and therefore a reduction of the protective action) to the core envelope and secondly (as a function of the core composition) can give rise a xe2x80x9cbleedingxe2x80x9d of the core into the material of the envelope and the basic composition. In addition, the intimate full-surface contact between the individual layers can lead to reactions occurring in the boundary layers which are undesired, particularly between the envelope and the outer layer.
The second important disadvantage of this prior art is that for initiating the dissolving of the enveloping layer the temperature and in particular the contact time with the washing solution is used as the triggering factor, which consequently clearly limits the practical usability of the products described.
PCT application WO 95/29982 discloses a dishwashing machine rinsing agent with a delayed release of a clear rinsing agent in the form of a nonionic surfactant, which together with an inorganic builder salt forms a core particle, which is provided with a wax-like covering in order to ensure the delayed release. This covering is a substance which does not melt at the operating temperatures encountered during the cleaning cycle, but which at alkaline pH-values is so gradually chemically disintegrated that there is still an effective clear rinsing agent quantity present at the end of the main cleaning cycle and is transferred into the rinse clear cycle.
It is disadvantageous that the covering is rendered soluble by chemical saponification at alkaline pH-values, so that the time at which the clear rinsing substance is released from the core is a function both of the temperature and the length of the main cleaning cycle. The patent application contains no teaching as to how a product is to be formulated with which the clear rinsing agent can be released in all washing programs of any machine type only during the rinse clear cycle. Finally the product is a mixture of granular cleaning agents and granular clear rinsing particles.
In view of the prior art described, the problem of the present invention is to provide a composition making it possible to release at different, defined times simultaneously charged products with different functionalities. The aim is to achieve this without significant restriction to the choice of the materials to be combined together.
According to the invention this problem is solved by a composition characterized by a basic composition evolving its function essentially following addition to a first water filling of the water tank, in the form of a tablet, and at least one particle with at least one core comprising at least one substance, which evolves its function substantially after an at least partial emptying of the first water filling from the water tank and the inflow of fresh water thereto, and a covering substantially completely surround the core or cores and comprising at least one compound, whose solubility increases with decreasing concentration of a specific ion in the surrounding medium, the at least one particle being so arranged in or on the tablet that the surface of the particle or particles at the most is in partial direct contact with the surface of the basic composition surrounding the same, and the concentration of the specific ion in the local environment of the particle or particles is sufficiently high up to a substantially complete dissolving of the tablet to prevent a significant dissolving of the covering or a significant detachment of the covering from the core or cores.
Preferably the or all the particles are received in at least one tablet cavity completely surrounded by the basic composition and having a larger volume than the or all the particles received in the particular cavity.
In an alternative, the particle or particles can be loosely arranged in the interior of the cavity.
In a particularly preferred embodiment of the invention the particle or particles are fixed in the interior of the cavity.
According to the invention the particle or particles are fixed in the interior of the cavity by an adhesive.
In an alternative embodiment of the invention the cavity is placed substantially centrally in the tablet interior.
The tablet has a single, substantially spherical cavity.
According to the invention the cavity receives a single, substantially spherical particle, whose external diameter is smaller than the internal diameter of the cavity.
According to an alternative embodiment of the invention the or all the particles are received in at least one cavity of the tablet, which is only partly surrounded by the basic composition.
The cavity is preferably a depression in one of the surfaces of the tablet, in which the particle or particles are at least partially received.
The particle or particles are so received in the cavity or depression that it or they do not project over the surface or surfaces of the tablet.
According to an embodiment of the invention the cavity or depression has a substantially circular cross-sectional face parallel to one of the surfaces to which it opens or in which it is located.
According to a particular embodiment of the invention the cavity or depression only opens to such an extent to the surface or surfaces that the particles received therein cannot pass through the opening or openings of the cavity or depression.
Preferably the particle or particles are loosely arranged in the cavity or depression.
It is also possible for the particle or particles to be fixed in the cavity or depression, said fixing preferably taking place with an adhesive.
In preferred manner according to the invention the covering comprises at least one compound, which is not or is only slightly soluble at the concentration of the specific ion prior to the inflow of fresh water and at the concentration of the specific ion following the inflow of an adequate fresh water quantity has such an adequate solubility that it is so substantially dissolved or detached from the core or cores that an at least partial escape of the core material into the surrounding medium is possible.
Preferably the solubility of the compound increases with decreasing OHxe2x88x92 ionic concentration and therefore decreasing pH-value in the surrounding medium.
Preferably the compound comprises a polymer, in particularly preferred manner a pH-sensitive polymer, which comprises at least one repeat unit, which has at least one basic function, which is not part of the polymer backbone chain.
In a preferred embodiment the polymer comprises at least one repeat unit, which is based on a compound selected from the group comprising vinyl alcohol derivatives, acrylates or alkyl acrylates having said basic function.
According to a special embodiment of the invention the polymer is a carbohydrate functionalized with said basic function.
The aforementioned basic function is preferably an amine, in particularly preferred manner a secondary or tertiary amine.
According to an alternative, the repeat unit is based on a compound having the following formula III: 
in which G is a linking group selected from xe2x80x94COOxe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94NHCOxe2x80x94, xe2x80x94NHCONHxe2x80x94, xe2x80x94NHCOOxe2x80x94, xe2x80x94OCONHxe2x80x94, or xe2x80x94OCOOxe2x80x94, each R1 independently of one another is hydrogen or an alkyl group with 1 to 3 carbon atoms, each R2 independently of one another is hydrogen or an alkyl group with 1 to 5 carbon atoms, and x is an integer from 1 to 6.
Preferably the repeat unit is based on a compound with the following formula IV: 
in which R1 independently of one another is hydrogen or an alkyl group with 1 to 3 carbon atoms, R2 independently of one another hydrogen or an alkyl group with 1 to 5 carbon atoms and x is an integer from 1 to 6.
According to another embodiment of the invention the basic function is an imine or a basic, aromatic N-containing group, preferably a pyridine group or an imidazole group.
According to a further embodiment the pH-sensitive polymer is a polymer derived from chitosan.
The invention finally proposes that the compound comprises K-carrageenan.
According to the invention the solubility of the compound increases with decreasing H+ ionic concentration and therefore increasing pH-value in the surrounding medium.
The compound preferably comprises a polymer.
According to an embodiment of the invention the compound comprises a pH-value-sensitive polymer, which comprises at least one repeat unit, which is based on a compound comprising an acid function.
According to an alternative the polymer comprises at least one repeat unit, which is based on a compound selected from the group comprising vinyl alcohol derivatives, acrylates or alkyl acrylates comprising said acid function.
The polymer is preferably a carbohydrate functionalized with said acid function.
In particularly preferred manner the acid function is a carboxyl group.
According to an alternative the repeat unit is based on a compound with the following formula V: 
in which G is a link group selected from xe2x80x94COOxe2x80x94, xe2x80x94OCOxe2x80x94, xe2x80x94CONHxe2x80x94, xe2x80x94NHCOxe2x80x94, xe2x80x94NHCONHxe2x80x94, xe2x80x94NHCOOxe2x80x94, xe2x80x94OCONHxe2x80x94 or xe2x80x94OCOOxe2x80x94, B independently of one another a hydrocarbon group selected from straight or branched, saturated or unsaturated, optionally substituted alkylene, arylene or aralkylene, Ak is hydrogen or an alkyl group, preferably with 1 to 4 carbon atoms, x, y and z independently of one another are either 0 or 1 and w is an integer from 1 to 3.
The repeat unit is preferably based on a compound with the following formula VI: 
in which B independently of one another is a hydrocarbon group selected from straight or branched, saturated or unsaturated, optionally substituted alkylene, arylene or aralkylene, Ak is hydrogen or an alkyl group, preferably with 1 to 4 carbon atoms, y and z independently of one another are either 0 or 1 and w is an integer from 1 to 3.
Preferably the pH-sensitive polymer is derived from a polysaccharide by partial esterification of some of its free hydroxyl groups with a polycarboxylic acid and/or by partial etherification of some of its free hydroxyl groups with a product obtained by esterifying one mole of a polycarboxylic acid with 1 mole of a polyol.
According to the invention the core or cores comprise at least one material selected from the group consisting of fragrances, disinfectants and pH-indicators.
According to an embodiment of the invention the core or at least part of the cores is in the form of an encapsulated liquid.
In particularly preferred manner the core or at least a part of the cores is in a solid form.
The composition according to the invention is characterized in that it solves the set problem with excellent results. The basic composition in the form of a tablet is dissolved following addition to the water filling of the water tank and can evolve its corresponding, intended action (cleaning, deliming, etc.). The particle located in or on the tablet contains as the core material that substance or substances evolving their main function only after an at least partial emptying of the water tank and the inflow of fresh water. The most varied substances can be used, e.g. fragrances, disinfectants, pH-indicators, etc.
Said substance or substances are protected by a covering, which at the ionic concentration, e.g. the pH-value and optionally the temperature of the first water filling of the water tank are stable and do not or do not significantly dissolve or become detached. Only when there is a significant drop in the ionic concentration or the pH-value through an at least partial emptying of the water tank and the inflow of fresh water, i.e. by dilution, is the solubility of the covering material reduced to such an extent that it rapidly dissolves or becomes detached and the actual active core material is released into the surrounding medium.
Provided that charging does not take place by special charging or dosing aids, which can hold back the particles according to the invention, the particles according to the invention should be sufficiently large to ensure that during the emptying of the water tank they are not discharged to a significant extent.
It is important for the solution according to the invention that the surface of the particle at most is in partial direct contact with the surface of the basic composition of the tablet surrounding it. This can take place in ways specifically described and represented in the application, but also in any other way achieving the sought objective. Examples are the loose arrangement of a smaller particle in a larger cavity and fixing a smaller particle in a larger cavity in such a way that there is no or only a partial contact between the particle and the basic composition of the tablet, etc. Compared with the prior art this constellation offers the advantage that during the production process, e.g. the moulding of the individual constituents taking place in successive steps, a deformation and possibly resulting damage to the core or cores and/or the covering is reliably avoided, because this could give rise to a reduction of the protective action of the core covering. If it is ensured that no pressure is exerted on the particle during any phase of the production process, it is possible to reliably prevent that in the case of specific core compositions there can be a xe2x80x9cbleedingxe2x80x9d thereof into the material of the covering and the basic composition. It can finally be advantageous for specific compositions of the covering or the basic composition to avoid an intimate, full-surface contact, because otherwise undesired reactions could arise in the boundary layers.
The term xe2x80x9clocal environmentxe2x80x9d, as used in connection with the particles according to the invention, indicates the immediate environment of said particles. The ionic concentration in said local environment of the particle is the determinative factor for the stability thereof. With the products according to the invention the ionic concentration in this local environment is determined at least up to a substantially complete dissolving of the tablet by the ions dissolving therefrom. Preferably the origin of the xe2x80x9cspecific ionxe2x80x9d, at least in a first phase following the addition to the water filling of the water tank, is consequently a compound from the basic composition forming the tablet or is produced by it in the surrounding medium. Typically these are OHxe2x80x94 ions (with basic cleaning agents) or H+ ions (with acid deliming agents), whose concentration can in both cases be expressed as the pH-value.